Vineyard IPM Scouting Report for week of August 31, 2009

UW-Extension Door County and Peninsular Agricultural Research Station

Sturgeon Bay, WI

Botrytis Bunch Rot

A number of bacterial and fungal organisms can infect

grapes causing bunch rot, however, botrytis is the most

important. Botrytis can remain dormant as sclerotia

on canes, last seasons cluster stems and on mummified

grape berries. The spores of botrytis are spread by

wind. Although succulent grape tissue (shoots and

flowers) can be infected in spring, often botrytis is con-

sidered a late season disease of developing and mature

grape clusters. Botrytis infection often occurs during

wet weather conditions in which grape clusters remain

wet for an extended period of time (15 hours or more).

Temperature also impacts botrytis infection with bo-

trytis infecting berries when temperatures are between 53 to 86° F. Infection of grape

berries can occur with as little as 4 hours of wetness when temperatures are within the

ideal range for infection (53 to 86° F). As the length of time of berry wetness increases,

the greater the potential for berry infection. Recent cool temperatures and the heavy

morning dews likely are extending grape cluster wetness that may result in botrytis infec-

tion. Botrytis will also infect berries more readily that have been injured by hail, insects,

and animals.

To reduce botrytis infection, good vineyard sanitation and canopy management practices

should be implemented. Last season’s grape cluster stems and mummified berries should

be removed during pruning from the vineyard to reduce the spore sources. Leaf thinning

should occur early in the season to develop the waxy cuticle of the grapes quickly, there-

fore forming a barrier that reduces the potential for infection. Air circulation is im-

proved around grape clusters also by leaf thinning which results in moisture evaporating

quickly, reducing the potential of botrytis infection. Fungicides also can penetrate deeper

into the grape clusters when leaves are removed. Be careful when leaf thinning late in the

season as sunscald can occur on grapes that have not been acclimated to sunlight. Early

exposure of grape berries (pea sized) results in a thicker layer of wax and a thicker berry

skin which results in resistance to sunburn and botrytis.

Damage to the grape fruit skin from animal or insect pests, hail, and even powdery mil-

dew provides an ideal environment for botrytis infection. Grape berries in which the skin

has been compromised will likely need to be protected with fungicides to prevent botrytis

infection. A number of fungicides are listed in the Midwest Commercial Small Fruit and

Grape Spray Guide 2009 or see Table on following page. Remember to pay attention to

the pre-harvest interval of any pesticides applied.

Fungicide Rate per acre PHI1 (days)

Adament2 50WG 6-7.2 oz 14

Elevate 50WDG 1 lb 7

Endura 8 oz 14

Pristine 8-12.5 oz 14

Rovral 4F 1.5-2 pints 7

Scala SC 18 oz 7

Vangard 75WG 10 oz 7

Fungicides for the management of botrytis bunch rot in grapes.

1The time interval between the last application and harvest. 2Do not apply to Concord grapes.

Grape IPM Field Days-Post Update

Thanks to all who participated in the 2009 Grape IPM Field Days. From the three sites

(Viroqua, St. Croix Falls, and Sturgeon Bay) approximately 50 participated. Also thanks

to site hosts, Tim Rehbein, Ruth Hilfiker, Kevin Schoessow, Jason Fischbach, and Rich-

ard Weidman. A special thanks to our speakers, Rufus Isaacs, Michigan State Univer-

sity, Tim Martinson, Cornell University, Dan Mahr, Patty McManus, and Steve Jordan

from the University of Wisconsin-Madison. The 2009 Grape IPM Field Days were sup-

ported by grants from the EPA-Pesticide Environmental Stewardship Program and the

North Central Risk Management Education Center.

Rufus Isaacs (center) dis-

sects a grape cluster to

show participants a grape

berry moth larvae at the

2009 Grape IPM Field

Day held at the Peninsu-

lar Agricultural Research

Station in Sturgeon Bay.

Take a look at some of the grape pests that participants saw and learned

about at the 2009 Grape IPM Field Days.

Grape Filbert Gall At left is a rarely seen gall

caused by the gall maker midge

Schizomyia coryloides. Located

within each pointed protuber-

ance is a developing larvae.

These galls are seldom harmful

to grapes unless extremely large

numbers are present.

Grape Tumid Gall Also called grape tomato gall.

The gall is caused by the fly

Janetiella brevicauda. Larva

develop in the galls, but as the

photo shows, the larva have

eaten their way out of the gall

and dropped to the ground to

pupate. Grape tumid galls are

seldom harmful but were appar-

ent on Frontenac in Northeast-

ern vineyards this year.

Grape Berry Moth (GBM)

The grape berry shows distinct

reddish/purple discoloration

where a grape berry moth entered

the grape berry. Also apparent is

webbing, all suggestive that grape

berry moth is present. Interest-

ingly, at the Peninsular Agricul-

tural Research Station, GBM

pheromone traps only caught one

GBM, but wild grapes nearby the

vineyard were heavily infested

with GBM.

What’s lurking in or near the vineyards this week?

Grape berry moth symptomology on wild grapes near Sturgeon Bay, WI

Downy mildew (right) Downy mildew symptomol-

ogy on wild grapes near

Sturgeon Bay, WI

Powdery mildew On wild grapes near Sturgeon Bay, WI

Phenoxy herbicide damage On wild grapes near Sturgeon Bay, WI

Fruit development on mature grape vines at Peninsular Agricultural Research Station in

Sturgeon Bay, Wisconsin.

Foch August 31, 2009 La Crosse August 31, 2009

La Crosse August 31, 2009 Foch August 31, 2009

Foch August 31, 2009 La Crosse

August 31, 2009

Vine development of Foch and La Crosse in the 2nd year at the Spooner Agricultural

Research Station.

Fruit development on mature grape vines in Vernon County.

Date 2009 2008 5 Year Average

7/19 961 1038 1109

7/26 1079 1176 1246

8/2 1200 1313 1402

8/9 1330 1450 1544

8/16 1476 1567 1661

8/23 1579 1707 1776

8/30 1659 1813 1890

Weekly Degree Day1 at Base 50 Accumulation at Peninsular Agricultural

Research Station in Sturgeon Bay, WI

Date 2009 2008 3 Year Average

7/19 1211 1273 1399

7/26 1324 1419 1545

8/2 1437 1582 1724

8/9 1575 1719 1874

8/16 1732 1833 2011

8/23 1839 1987 2146

8/30 1932 2104 2272

Weekly Degree Day1 at Base 50 Accumulation at West Madison

Agricultural Research Station, Madison, WI

1Modified method

1Modified method

Please scout your vineyards on a regularly scheduled basis in an effort to manage problem pests. This report

contains information on scouting reports from specific locations and may not reflect pest problems in your

vineyard. If you would like more information on IPM in grapes, please contact Dean Volenberg at (920)746-

2260 or dean.volenberg@ces.uwex.edu

Understanding Pesticides

An Introductory Course for Commercial Fruit Growers

Are you familiar with all the new pesticide groups?

Do you understand how pesticides work?

Do you know the difference between a residue and a tolerance, and how these relate to the PHI?

Do you know all of the legal aspects of a pesticide label?

Do you understand how pests develop resistance to pesticides? And how to avoid resistance?

If you answered “no” to any of these questions, you may wish to take this UW-Extension workshop for fruit

growers.

Course objectives. The purpose of this course is to provide basic information on pesticides, such as their tox-

icity, the laws that govern their use, and how pests develop resistance to them. The intent of the course is not

to answer specific questions on controlling specific pests, but instead, to lay a foundation for a better under-

standing of safe and effective pesticide use. Much of the material in the introductory morning sessions

(Pesticide Overview Modules) will be similar to content in Wisconsin’s Pesticide Applicator Training pro-

gram. If you have Pesticide Applicator Certification, some of this material will be a review; if you are not cer-

tified, this information will be a useful introduction to some of the subjects covered in the certification training

program. (But note that this short course is not part of the formal Pesticide Applicator Training pro-

gram.)

Who may attend? The target audience is all commercial fruit growers, whether just beginning or with a life-

long experience growing fruit. Those people new to farming will likely benefit the most.

When is the workshop? Saturday, November 7, 2009; 8:30 – 5:15.

What is the location? University of Wisconsin Extension’s Pyle Center, on the UW – Madison campus.

What is the cost? The registration fee of $40/person covers facility costs, refreshment breaks, lunch, and

handouts.

Who are the instructors?

Dr. Dan Mahr is Professor of Entomology and Extension Fruit Crops Entomologist, UW-Madison.

Dr. Patty McManus is Professor of Plant Pathology and Extension Fruit Crops Pathologist, UW-Madison.

Dr. Jed Colquhoun is Associate Professor of Horticulture and Extension Weed Scientist, UW-Madison.

The minimum enrollment for this course is 20 registrants by Friday October 16.

Registration will be capped at 48; registration is first-come, first served.

The final, fees-paid, registration deadline is Friday, October 23.

No on-site registration.

For more information, contact Dr. Dan Mahr at 608-262-3228 or email dmahr@entomology.wisc.edu .

The Day’s Agenda

8:30 – Registration

9:00 – Pesticide Overview – Module 1

10:30 – Break

10:45 – Pesticide Overview – Module 2

12:00 – Lunch (provided with registration fee)

12:30 – Catch-up and discussion

12:45 – Fruit crop fungicides

2:00 – Break

2:10 – Fruit crop herbicides

3:25 – Break

3:40 – Fruit crop insecticides

4:55 – Catch-up; wrap-up; evaluations

5:15 - Adjourn

Specific topics to be covered in the morning modules include Pesticide Categories, Understanding Pesti-

cide Toxicology, Spectrums of Pesticide Activity, Pesticide Names, Pesticide Formulations, Pesticide Laws

and Regulations, the Pesticide Label, Reducing Pesticide Risk, Avoiding Pesticide Resistance, Pesticide

Movement in Plants, Pesticide Application, Understanding Label Rates, Biorational Pesticides, Pesticides for

Certified Organic Production.

In the afternoon, specialists will present information about the major groups of pesticides – fungicides,

herbicides, and insecticides. The emphasis will be on the characteristics and general uses of specific pesticide

groups. Discussions will include conventional and biorational products as well as those for certified organic

production.

Understanding Pesticides: An Introductory Course for Fruit

Growers Presented by University of Wisconsin – Extension; Saturday, November 7, 2009

Registration Form

Contact Name____________________________________________________________________________

Farm/Business___________________________________________________________________________

Address_________________________________________________________________________________

City____________________________________________ State________ Zip______________________

Phone ( )__________________________ Email___________________________________________

Name(s) of Attendee(s) (for name badges)

(1)_________________________________________ (2)_________________________________________

(3)_________________________________________ (4)_________________________________________

Registration fee is $40/person. Fee covers facility costs, handouts, lunch, and refreshments.

Final Registration Deadline: Friday October 23. You will be sent a registration acknowledgement.

Number attending: ______ Total amount enclosed @ $40 each: ___________

Make checks payable to: University of Wisconsin. (Sorry, we can not process credit cards.)

Mail form along with payment to: Fruit Growers’ Workshop

Department of Entomology

University of Wisconsin

1630 Linden Drive

Madison, WI 53706

Important – meal choice! Boxed lunches will include a sandwich, chips, fruit, beverage, and light desert.

Please check your choice of sandwich from the following list. If there is more than one attending from your

group on this registration form, place the initials of the attendee(s) next to the choice of sandwich(es).

Choice 1: Smoked turkey breast on cheese roll, with lettuce, tomato, onion. ________________________

Choice 2: Corned beef and baby Swiss on onion roll with lettuce, tomato, onion. ____________________

Choice 3: Pine nut humus & feta spread and veggies on sourdough (vegetarian).____________________

The following information is optional, but will guide us in developing the pro-

gram.

How long have you been farming? a. In the process of getting started.

b. 1-2 years

c. 3-5 years

d. 6-10 years

e. more than 10 years.

Have you taken the Pesticide Applicator Training Program to become a certified applicator? Yes No

What is your current total producing acreage of fruit crops? ____________ acres

What are the primary fruit crops that you grow? (Circle up to 3.)

apple cherry grape strawberry

blueberry cranberry raspberry other (please list)

_______________________________